Corrosion-resisting ferrous alloy adapted for forging and casting purpcses



Patentedv Oct. 16, 1934 PATENT OFFIE CORROSION-RESISTING FEBROUS ALLOY ADAPTED FOB FORGING AND CASTING PURPOSES Maurice Palmyre Fonld, Paris, France, assignor to Sooiete Anonyme Des Hauts-Fourneaux, Forges & Acierlea De Pompey, Paris, France No Drawing. Application September 15, 1933, Serial .No. 889,563. In France September 26,

The invention relates to corrosion-resisting ferrous alloys, and more particularly to those corro sion-resisting alloys which arerelated to pure iron in contradistinction with the non-rusting steels which contain a large proportion of special components.

The ferrous alloys of the class herein referred to are very pure ferrous alloys, which may contain small amoun of copper, tungsten or molybdenum, chromi nickel etc. They may. optionally contain silicon, according as the metal is "quiet" or foamy, but are, always practically free from carbon, phosphorus and sulphur, and it is difllcult, or even impossible, to cast them.

The present invention has for its object a ferrous alloy which resists corrosion, and can be forged or moulded, and which contains, in addition to the iron, approximately the following proportions of the following components:

Carbon less than 0.050% Manganese from 0.200 to 0.600% Silicon from 0.200 to 0.600% Phosphorus less than 0.020% .Sulphur less than 0.015% Copper from 0.300 to 0.600% Tungsten from 0.010 to 0.150%

The resistance to corrosion of this metal when "quiet" is not altered by the presence of manganese, even in a large proportion, such as 0.600%.

Into ,the known ferrous alloys above referred to fromv 0.01 to 0.4% of chromium was sometimes added in order to improve the mechanical features. Inasmuch as, in the alloy according to the invention, the proportion of manganese is between 0.2 and 0.6%, it is no longer necessary to employ chromium in order to obtain the same tensile strength.

The alloy according .to the invention, in the annealed state, shows the following mechanical features, as tested upon standard samples:

Coemcient of elasticity E from 28 to 32 kgs.

55.74 mm. diameter is-cut in a casting and is pierced at its centre with a circular hole of 10 mm. diameter; the test piece is lathe-turned so as to provide a symmetrical bevelled outline, having a constant thickness of 3 mm. within a circle hav- 3 Claims. (01. -1

ing a diameter of 20 mm., and then regularly decreasing to 1 millimetre at the periphery. The sample is then polished, cleaned, and pickledsuccessively in concentrated baths of nitric acid and hydrochloric acid, until the crystalline texture appears, and it is finally immersed for five minutes in a solution of sulphuric acid at by weight, at a temperature of C. The sample is then removed and washed, and is immersed before any commencement of oxidation, in a solution of sulphuric acid at 30% by weight of acid S04E12 at a temperature of 17 C., in an inclined position with" reference to the vessel containing the solution,

and it is allowed to remain therein for-i8 consecutive hours.

At the end of this time, the test piece is re moved, and the amount of iron dissolved is determined by oxidizing the ferrous sulphate by means of potassium permanganate. The degree of corrosion is found to be comprised between 0.05

and lmilligramme of dissolved iron per square centimeter of surface of the test piece and per 24 hours.

The homogeneity of this steel can be shown by a macrographic examination of a section of the rolled metal,- perpendicular to the direction oi rolling, that is perpendicular to the axis of the original ingot. The macrographicsample may be prepared by a prolonged attack by hot sulphuric acid or the test may be made with Bauniann paper.

Whilst the known alloys of the above-mentioned class, whether quiet or foamy, show a great heterogeneity of structure between the centre and the periphery, the alloy according to the present invention is remarkably homogeneous.

Owing to the manganese, the forging quality of this alloy is improved, throughout the whole range of temperatures, as compared with the similar 65 metals now in use.

Due to its composition, this alloy can be used for casting purposes, whilst theknown similar alloys cannot be cast or yield blistered castings.

The alloy according to the invention may be produced by any of the usual metallurgical proc asses, and particularly in the Siemens-Martin furnace or the electric furnace, after acomplete refining under a very calcareous slag; until a bath of very soft iron is obtained; the slag is then re moved and a fresh calcareous slag is formed, and

at this time, the manganese can be introduced in any desired form, whether as since-manganese,

retro-manganese or super-refined manganese.

The tungsten may be added at the same time as the manganese, or subsequently; the copper 0 .sea water and to sea spray than iron of very great purity.

Having now described my invention what I claim as new and desire to secure by Letters Patentis:

1. A corrosion resisting iron alloy particularly adapted to resist the action of acid media, such as sulphuric acid, comprising the following constituents, in the following approximate'proportions by weight:

Carbon less than 0.050%

\ Manganese from 0.200 to 0.600% Silicon from 0.200 to 0.600% Phosphorus less than 0.020% Sulphur less than 0.015% Copper from 0.300 to 0.600% Tungsten from 0.010 to 0.150% Iron the rest 2. An acid resisting casting consisting of a ferrous alloy comprising the following ccnstitutents, in the following approximate proportions by weight:

Carbon less than 0.050% Manganese from 0.200 to 0.600% Silicon from 0.200 to 0.600% Phosphorus less than 0.020% Sulphur"; less than 0.015% Copper from 0.300 to 0.600% Tungsten from 0.010 to 0.150% Iron the rest 3. Anacid resisting forged ferrous alloy comprising the fol awing constituents, in the following approximate proportions by weight:

Carbon less than 0.050% Manganese from 0.200 to 0.600% Silicon from 0.200 to 0.600% Phosphorus less than 0.020% Sulphur less than 0.015%

Copper from 0.300 to 0.600% Tungsten from 0.010 to 0.150% Iron the rest MAURICE PAIMYRE FOULD. 

